As a conventional sheet for attachment to the skin of the human body or others, a skin care sheet impregnated with a liquid such as a cosmetic preparation (a liquid-impregnated sheet for living-body application) is being used. The skin care sheet as typified by a facial mask sheet simply allows the skin to be maintained in a highly wet or moist state, and a wide variety of commercial products is now being developed. As a material for the sheet, a woven fabric or a nonwoven fabric, each comprising (or made of) a fiber, is usually employed, and the nonwoven fabric is widely used because of costs. A spunlace nonwoven fabric comprising a cellulose-series fiber (as typified by a cotton having a high hydrophilicity) as a main component is often used as a nonwoven fabric sheet for impregnation with a cosmetic preparation. However, the spunlace nonwoven fabric of the cellulose-series fiber causes irritation to the skin and has an insufficient fitting property (or application property) to the skin.
Japanese Patent No. 3944526 (Patent Document 1) discloses a living-body application sheet for liquid (such as cosmetic preparation) impregnation, wherein an ultrafine fiber is present on a surface of the sheet in order to reduce the irritation to the face and improve the fitting property (or application property) to the face, specifically a skin application sheet for cosmetic preparation impregnation, wherein an ultrafine fiber layer which comprises at least 10% by mass of an ultrafine fiber with a fineness of at most 0.5 dtex and is placed on one surface or both surfaces of a hydrophilic fiber layer which comprises at least 50% by mass of a hydrophilic fiber, the hydrophilic fiber layer and the ultrafine fiber layer are integrated, and the ultrafine fiber layer is to be the surface which contacts with the skin. This document discloses that the ratio of the hydrophilic fiber is 10 to 70 parts by mass (preferably 15 to 50 parts by mass) relative to 100 parts by mass of the application sheet.
For a skin care sheet (a sheet for cosmetic preparation impregnation), it is necessary to combine capacities to retain and release a cosmetic liquid, although the application sheet has a difficulty in the compatibility between the liquid retentivity and the releasability. Further, the document is silent on the fiber diameter distribution of the ultrafine fiber. Moreover, in the case of a process for forming a nonwoven fabric by splitting a splittable conjugate fiber, it is difficult to obtain a nonwoven fabric comprising uniformly and moderately entangled fibers, the resulting nonwoven fabric has a low adhesion to the skin, causes irritation to the skin, and is less comfortable to wear. For example, the nonwoven fabric is often scratchy or unpleasant to the touch. In particular, when the nonwoven fabric is impregnated with a liquid component and contacted with (or applied to) the skin, the adhesion of the impregnated nonwoven fabric to the skin is insufficient. For example, when the fabric is left on the skin for a long time, the fabric often peels off or slips off the skin. In particular, since a sheet impregnated with a cosmetic preparation or others is used for the purpose of permeating the cosmetic preparation or others into the skin, the sheet requires a capability to adhere to the skin over a wider area for a long time in use. The peeling-off or slipping-off due to a low adhesion of the sheet discomforts or dissatisfies a user. When the sheet is also used as a kind of amenity product, which is pleasant or comfortable, the sheet requires less irritation and higher adhesion to the skin to give a user a feeling of satisfaction. In addition, the comfort (or satisfaction) produced by a long-lasting high adhesion of the sheet is a key factor in evaluating a commercial value. Moreover, in response to the changes in society, the sheet for cosmetic preparation impregnation is being used in many different situations or states. For example, for working women, since it is difficult to spare their precious time for skin care, such women use the sheet in a straighten up position (or with the upper part of the body elevated) to no small extent, e.g., while doing housework, watching TV, or reading books. Accordingly, there is a demand for a sheet for cosmetic preparation impregnation, having a higher adhesion and a higher liquid-retention (liquid-holding capacity).
Further, the sheet for impregnation with a cosmetic preparation is being used in order to not only achieve an efficacy on the skin of an active component contained in a liquid (liquid component) but also produce a comfort (or a good feeling) in use, and the comfort is a factor of inciting buying inclination. Thus the sheet is also worth using as an amenity product. This is a reason for a recent increasing demand for the sheet. Specifically, a desired sheet has a soft “feel” against the skin and provides both the feeling that the skin is fully covered with a liquid coat of a cosmetic preparation and the “adhesion feeling” as clung to the skin for a long time.
In particular, a demand for a sheet impregnated with a cosmetic preparation or others, as typified by a facial mask sheet, is now being increased, and accordingly a sheet having a higher performance and a greater comfort is required. The sheet is primarily used to keep the skin highly wet (or moist) during use with various cosmetic preparations each having different effects. Accordingly, it is necessary for the sheet to have a liquid retention suitable for keeping the skin highly wet (or moist).